INFLUENCE OF SIZE AND ASYMMETRY OF SEXUAL CHARACTERS IN THE ROOSTER AND HEN ON THE NUMBER OF EGGS LAID

The quality of secondary sexual characteristics is thought to signal t he desirability of an individual. That the attractiveness and/or quali ty of an individual, male or female, can have an effect on reproductio n is also well known, In the present experiment we studied how asymmet ry and size of secondary sexual characteristics in hens and roosters ( Gallus gallus domesticus) affected the egg laying of hens, The strain used was a relaxed selection line of Brown Leghorn with a relatively l ow egg production (approx. 0.6-0.8 eggs/day). Each hen spent 24 h/week with the rooster, there were 4 females/rooster, in total 32 roosters and 127 hens. We found a significant effect of wattle asymmetry of roo sters on the number of eggs laid by hens mated with them, hens mated w ith symmetrical males laying more eggs in total (r(s) = 0.50, P = 0.00 3, Spearman Rank Corr.), hens mated with roosters with larger wattles laid fewer fertilised eggs (r(s) = -0.40, P = 0.02, Spearman Rank). No effect was found for asymmetry of the wattles of the hens on total eg g production (r(s) = 0.10, P = 0.36, Spearman Rank) or on fertilised e ggs (r(s) = 0.020, P = 0.85, Spearman Rank). These results indicate th at the original factors that affected reproduction in the wild ancesto r of the domestic hen, e.g., male quality, might still be important in affecting the egg production of domestic poultry.